1. Field of the Invention
The present invention relates to a novel organopolysiloxane, a method for using the organopolysiloxane, a cosmetic containing the organopolysiloxane, and a method for producing the organopolysiloxane.
2. Description of the Related Art
A silicone oil has been conventionally blended into a cosmetic as an oil material to suppress stickiness and an oily feeling of the cosmetic. Meanwhile, the silicone oil is prone to many shortcomings such as undesirable fitting to the skin and insufficient moist feeling. To solve these problems, technical efforts have been made to provide an organopolysiloxane with improved surfactant property and sense of touch in use by introducing a polyether group into a dimethyl polysiloxane as a hydrophilic group (Japanese Unexamined Patent Publication No. S61-123635).
Nevertheless, despite easy design structure in this type of silicone, a silicone whose degree of polymerization is high may involve a residual unreacted polyether and thus a problematic surfactant performance, resulting in unstable cosmetic sustainability. Moreover, emulsion stability is achieved by introducing a silicone whose structure is branched, but unfortunately, a method for producing a silicone compound by introducing the branched structure is not fully simplified for production (Japanese Unexamined Patent Publication No. 2002-179797).
In addition, an (AB)n type organopolysiloxane copolymer in which a silicone unit and a polyoxyethylene unit are alternately bonded is proposed (Japanese Unexamined Patent Publication No. H4-21 1605: Japanese Unexamined Patent Publication No. H4-234307; Japanese Unexamined Patent Publication No. H 5-163436). This type of alternating copolymer is advantageous in the reduction in residual unreacted organopolysiloxane and unreacted polyether. However, a silicone having the linear repeating unit may provide senses of weight and stickiness for a cosmetic containing the same.
Another copolymer, such as an AB type or an ABA type organopolysiloxane copolymer, in which only 2 or 3 polyether units such as a silicone unit and a polyoxyethylene unit are bonded, is proposed. However, emulsion stability therein is insufficient as a surfactant (Japanese Unexamined Patent Publication No. 2005-344076; Japanese Unexamined Patent Publication No. S62-195389; Japanese Unexamined Patent Publication No. 2009-511710; Japanese Unexamined Patent Publication No. 2009-511712). Accordingly, production of an organopolysiloxane copolymer has conventionally required additional improvements to serve as a more useful surfactant and cosmetic ingredient.